Study on crosswind effects of high-speed trains during exiting tunnels
In order to study the influence of crosswind effects on the aerodynamic characteristics of high-speed trains(HST)in the process of exiting tunnels,a 3D numerical model including tunnel,train and crosswind was established based on the three-dimensional,compressible and unsteady characteristics of the flow field.The influence of crosswind effects on the distribution of the flow field and the pressure on the train surfaces in the process of exiting the tunnel was analyzed,and the mechanism of the aerodynamic load change was revealed.The numerical simulation was verified by comparison with the moving model test results.The results show that significant spatial effects of the flow field distribution exists during a train exiting a tunnel under crosswind,and the flow field near the tunnel outlet exits obvious unsteady characteristics.Compared with the non-crosswind,the pressure variation amplitude of the bottom of the train under crosswind increases by 60%,the pressure variation amplitude of the windward side and the top of the train increases by 38.1%and 28.6%,respectively,the pressure variation amplitude of the leeward side varies by 4.8%,and the pressure distribution of the leeward side is least affected by crosswind.The pressure distribution of the train under crosswind is least influenced by crosswind,and the pressure distribution of the train surfaces is least influenced by crosswind.The pressure distribution is minimized by the crosswind;the crosswind effect leads to significant changes in the aerodynamic characteristics of the train,and the magnitude of the aerodynamic load change is much larger than that of the aerodynamic characteristics of the train changes significantly effected by crosswind effects,and the change magnitude of aerodynamic loads are much larger than that of the non-wind condition.In the non-wind condition,the change amplitude of the side force and lift of the tail vehicle are the largest.In the contrast the change amplitude of the side force of the head vehicle is the largest under crosswind,and the overturning risk is the largest.